Cruisers Forum
 


Reply
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 18-08-2020, 11:07   #91
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,342
Send a message via Skype™ to Auspicious
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by rslifkin View Post
As much as we might all think it's stupid, I can see the logic. Get rid of all weight that isn't providing a direct benefit, but keep anything you find beneficial. I guess for some, a large quantity of beer falls into the second category.
*grin* In that case I'd suggest removing the bow thruster when pulling off the door to the head.

Quote:
Originally Posted by Dockhead View Post
If blanking plates on thruster tunnels provided a material edge I think you can be really sure that they would always be on. Those guys are always analyzing every tiny thing they can do which influences performance by even ridiculously small margins by our standards.
I suggest they are subject to confirmation bias.

You can write to my alma mater Webb Institute and ask. I suggest Prof Rick Neilson who is emeritus (thus has time) and still quite active. You could also check with University of Delft Marine Technology (Technische Hogescule Delft Schapsbaeukunde (sp?) when I taught there briefly on an IAESTE exchange in the 80s). You can also try Newcastle University that has a good naval architecture program. The libraries of SNAME or RINA could help also.

Heck, any place with a decent hydrodynamics or fluid dynamics program will be able to tell you about the increase in resistance from flow perpendicular to an open tunnel.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 18-08-2020, 11:26   #92
Registered User

Join Date: Oct 2014
Posts: 5,220
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Highly recommend the installation of JetThrusters for both bow and stern placement to provide for complete control and negligible drag as their is not large tunnels or large storage area utilizations.

An example of such can be viewed in this video and many other videos.



https://jetthrusteramerica.com/

Note these small diameter but high speed, high powered thrusters will continue to be effective even when the craft is making headways, [forward or reverse] whereas traditional bow thrusters tend to lose a lot of their capacity due to the fore or aft streaming of motion when a boat is making headway thereby inhibiting full intake of water into the tunnel.

As to med mooring under adverse conditions, e.g., strong cross winds or current, I believe attempting to due such in the presence of adjoining boats is just foolhardy, and very reckless regardless of one's so called "expertise" and experience, especially if the vessel is not equipped with powerful fore AND aft side thrusters so as to be able to readily move against such strong external influencing forces. One does not have the privilege to endanger a boat that is lying moored. If an allision occurs the fault lies entirely with the reckless skipper who is attempting to moor under adverse conditions. And an allision is a high probability outcome when conditions are adverse. If there are no adjoining boats then what the heck it is the skipper's / owner's prerogative to endanger their own boat to damage, but the skipper / owner never has the privilege to place their crewmates into danger. Crew should stand clear of impediments that may be allision hazards when the skipper fails at their maneuvering attempt. As a crewmember, just let the boat bash and stay the hell out of the way. Let the skipper figure out their own mess up. If you first avoid the potential of going up against another's vessel you will not be faced with the experience of trying to keep the crew of the boat that is also enduring an allision far away from the points of contact. People tend to always want to get involved in attempting to minimize damage to their own boats and they can easily get hurt or killed if the boats are of heavy displacement or conditions are rough. So one has to think not only of the safety of your own crew and vessel, but foremost of the persons on the other boats that one may have an allision and their vessel. Just do not attempt maneuvers that would endanger others or their property, that is the ultimate degree of poor mariner practice. Even if one is successful in accomplishing a med mooring in tight quarters to adjacent vessels under adverse conditions, all one has proven it that you are a reckless fool and a disgraceful skipper that should be given a harsh and sternly worded telling off to by both the shipmates onboard the vessel that performed the maneuver and the adjoining boats and persons all along the quay. Your stay should be a very unwelcomed one. Accomplishing a med mooring under adverse conditions in close proximity to other vessels is not something that one should feel to be an "fine accomplishment" or to be respected by others, it is just a exhibit of poor judgement and marinership and should be a badge of disgrace, not of honor.

Don't be like Nike, Just Don't Do It!!!! Await for proper mooring conditions or go elsewhere.
Montanan is offline   Reply With Quote
Old 18-08-2020, 11:40   #93
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,342
Send a message via Skype™ to Auspicious
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by Montanan View Post
Highly recommend the installation of JetThrusters for both bow and stern placement to provide for complete control and negligible drag as their is not large tunnels or large storage area utilizations.
A hole is a hole. Three moderate size holes vice two slightly larger ones? Have to run the numbers.

Space intrusion looks similar or more than an a conventional bow thruster.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 18-08-2020, 11:42   #94
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Ocala FL
Boat: 1979 Bristol 35.5 CB
Posts: 1,802
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

I wish we could see the lead up, how he got himself into the predicament in the first place. Judging by the flag, and him being pinned broadside, wind looks pretty straight onshore. Drop anchor and back in slowly, motor to adjust alignment.


Of course, I've never sailed there and Med mooring scares me to death, but this one looks pretty straightforward.


And after the initial performance, I would have fled to a different harbor in shame.
__________________
John Churchill Ocala, FL
NURDLE, 1979 Bristol 35.5 CB
Homeport currently Hudson Beach FL
sanibel sailor is offline   Reply With Quote
Old 18-08-2020, 11:52   #95
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,342
Send a message via Skype™ to Auspicious
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by sanibel sailor View Post
I wish we could see the lead up, how he got himself into the predicament in the first place. Judging by the flag, and him being pinned broadside, wind looks pretty straight onshore. Drop anchor and back in slowly, motor to adjust alignment.
We can only speculate. My guess is that he was running along the row of boats to close and being timid was going too slowly so he couldn't get the bow up into the wind. If that is correct, he *ahem* screwed himself.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 18-08-2020, 12:00   #96
Registered User
 
brendanwalls's Avatar

Join Date: Sep 2016
Location: Crownsville
Boat: 24ft Bristol Corsair
Posts: 95
Send a message via MSN to brendanwalls Send a message via Yahoo to brendanwalls Send a message via Skype™ to brendanwalls
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Talking of too much beer: the captain aboard the tanker that sunk off Mauritius three weeks ago was hosting a party at the time of the wreck, and had felt the need to go closer to shore to get a better wifi signal
brendanwalls is offline   Reply With Quote
Old 18-08-2020, 12:11   #97
Registered User
 
HeinSdL's Avatar

Join Date: Apr 2018
Location: Switzerland
Boat: X-Yachts X442
Posts: 407
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by Auspicious View Post
Delft Marine Technology (Technische Hogescule Delft Schapsbaeukunde (sp?)
Technische Universiteit Delft, faculteit van Werktuigbouwkunde en Maritieme Techniek. :-) At least that was its name in the late 80's/early 90's and where I spent 5 very interesting years!


Edit: You may recall its name as being Technische Hogeschool Delft, faculteit Scheepsbouwkunde, the former becoming TUD and the latter merging with the faculty of Mechanical Engineering (werktuigbouwkunde) both as mentioned above.
HeinSdL is offline   Reply With Quote
Old 18-08-2020, 12:23   #98
Registered User
 
HeinSdL's Avatar

Join Date: Apr 2018
Location: Switzerland
Boat: X-Yachts X442
Posts: 407
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by sanibel sailor View Post
I wish we could see the lead up, how he got himself into the predicament in the first place. Judging by the flag, and him being pinned broadside, wind looks pretty straight onshore. Drop anchor and back in slowly, motor to adjust alignment.
The difficulty is that you don't get hold of the bow mooring line until you have reached the quay with the stern. There is no anchoring involved. So to control the bow in this situation you would need to reverse smartly past one of the two boats already there and use them as 'support'. If all goes completely wrong and you end up side ways in that space then just let it be, use fenders as efficiently as possible and then pull the bow back out once you've got hold of the bow mooring line. In any case you can safely disregard the engine because it can help no more.
HeinSdL is offline   Reply With Quote
Old 18-08-2020, 12:29   #99
Registered User
 
Auspicious's Avatar

Join Date: Jun 2003
Location: Chesapeake Bay
Boat: HR 40
Posts: 3,342
Send a message via Skype™ to Auspicious
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by HeinSdL View Post
Technische Universiteit Delft, faculteit van Werktuigbouwkunde en Maritieme Techniek. :-) At least that was its name in the late 80's/early 90's and where I spent 5 very interesting years!


Edit: You may recall its name as being Technische Hogeschool Delft, faculteit Scheepsbouwkunde, the former becoming TUD and the latter merging with the faculty of Mechanical Engineering (werktuigbouwkunde) both as mentioned above.
Brilliant. That's it! I was there in late '81 and early '82. They let me teach in English, mostly in the model basin working on scaling of results. I still have a necktie from the William Froude Society that I treasure from that time. I lived in a house on Ternatestraat with a bunch of graduate students.

My first peer-reviewed paper came from that time.

Please forgive my spelling. It was quite long ago. My grip on languages other than English (I speak American and British *grin*) is marginal.
__________________
S/V Auspicious
AuspiciousWorks
Beware cut and paste sailors
Auspicious is offline   Reply With Quote
Old 18-08-2020, 12:30   #100
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 31,076
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by Montanan View Post
. . .As to med mooring under adverse conditions, e.g., strong cross winds or current, I believe attempting to due such in the presence of adjoining boats is just foolhardy, and very reckless regardless of one's so called "expertise" and experience, especially if the vessel is not equipped with powerful fore AND aft side thrusters so as to be able to readily move against such strong external influencing forces. One does not have the privilege to endanger a boat that is lying moored. If an allision occurs the fault lies entirely with the reckless skipper who is attempting to moor under adverse conditions. And an allision is a high probability outcome when conditions are adverse.. . . Accomplishing a med mooring under adverse conditions in close proximity to other vessels is not something that one should feel to be an "fine accomplishment" or to be respected by others, it is just a exhibit of poor judgement and marinership and should be a badge of disgrace, not of honor.. . .
Easy there, now, have you ever actually done any sailing in the Med?

This is all well and good in theory, but in practice you just don't have any choice. We do Med (and Baltic) mooring every day and in all kinds of weather -- it goes with the territory. Otherwise what are you going to do -- stand off and heave to for three days until the Meltemi dies down? No, we go in.



In fact rarely are boats damaged. The main thing is to keep straight and and have fenders out and don't abuse the throttle. A thruster helps enormously but even without a thruster it's not really dangerous, especially in a boat which is small enough to fend off a bit by hand if necessary. You don't need a stern thruster, you can displace the vessel sidewise with thrust and counter-rudder. You don't need a thruster powerful enough to hold the bow up against the wind, just enough to steer the bow a bit so that you can get in with your main engine thrust. And mostly the secret is getting lines on and hauling.

If you get blown onto an adjacent boat whilst Med mooring it's just not a big deal provided you're straight and fendered up. It's not considered bad form. The crew of the adjacent boat will help you off and into your berth. You get a line on to windward and haul yourself up. On a bigger boat you take a strategically placed line to an electric winch or warping drum. On a smaller boat you can use the main force of your crew too.

The video in the OP showed a really unusual cock-up. Normally you keep the boat straight, go easy on the throttle, lead a bit to windward, get lines on, and nothing gets scratched, even with the Meltemi howling abeam. The skipper in the OP just had zero skill and zero clue.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 18-08-2020, 12:33   #101
Registered User

Join Date: Oct 2014
Posts: 5,220
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by Auspicious View Post
A hole is a hole. Three moderate size holes vice two slightly larger ones? Have to run the numbers.

Space intrusion looks similar or more than an a conventional bow thruster.
A typical jet thruster opening is 60mm and traditional propeller thruster will be 182 mm ID. Area comparison: 2,826 sq. mm per thruster opening versus 26,000 sq. mm for each of the bow thruster openings; there be two of each, one port and one starboard. There is the ease and much greater manuevering capability of ease of installation of aft port and starboard jet thrusters, whereas I have yet to see a recreational boat with an aft tunnel thruster. So for the bow, that means 5,652 mm versus 52,000 mm.

The Jet Thruster does require a modest intake opening on the bottom of the hull to feed water to the pump. All rather similar to fresh water intakes for engines just at much greater pressure and volume. The jet thruster tends to be rather self cleaning if one regularly engages the passageways so as to cleanse the pipes. Kind of a pressure washer inside.

The jet thruster is rather immune to fouling with a mooring line since it is pushing away not sucking inwards like a bow thruster.

The jet thrusters do not lose much effectiveness when making headway beyond say two knots like a tunnel thruster will. Also a bow thruster is very prone to cavitation when placed under high speed when attempting to derive large thrust force because there is little to no advance of the vessel relative to the propeller. So when one needs the maximum force the thruster tends to cavitate and not yield extra gain.

"A bow thruster is usually designed to produce a specified force at
some ahead ship speed and on this basis the performance at ahead speed of
different size bow thrusters should be compared at a jet velocity that
varies inversely with duct diameter. One such comparison showed that a
smaller diameter duct produced less interaction (suction force) than a
larger diameter duct at a higher ahead speed. Perhaps more important was
the effectiveness of extending the duct beyond the hull (conceived as a
retractable pipe extension) in the reduction of hull suction effect."

The attached chart in indicative of the steep gradient of resistance relative to the diameter of openings and velocity of the vessel through the water. Do not this graph is for large ships so the diameters are in feet but the effect is similar when measured in smaller units, inches / mm. Big Openings Suck.

So a bow tunnel with 10 times the area of jet thrusters will be of much greater resistance drag.
Attached Thumbnails
Click image for larger version

Name:	resistance of thruster opening versus speed.PNG
Views:	57
Size:	61.6 KB
ID:	221528  
Montanan is offline   Reply With Quote
Old 18-08-2020, 14:05   #102
Registered User

Join Date: Oct 2014
Posts: 5,220
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Lest one not forget "The Other Forward!" when backing in at a fast pace, albeit straight on.

Montanan is offline   Reply With Quote
Old 18-08-2020, 15:28   #103
Moderator
 
Dockhead's Avatar

Cruisers Forum Supporter

Join Date: Mar 2009
Location: Denmark (Winter), Helsinki (Summer); Cruising the Baltic Sea this year!
Boat: Cutter-Rigged Moody 54
Posts: 31,076
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Now for the opposite experience:







That's med mooring. Single handed. Under sail. In 27 knots of wind. Yup.
__________________
"Parce que je suis heureux en mer, et peut-Ítre pour sauver mon ame. . . "
Dockhead is offline   Reply With Quote
Old 18-08-2020, 16:13   #104
Registered User

Join Date: Oct 2014
Posts: 5,220
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by Dockhead View Post
Now for the opposite experience:


That's med mooring. Single handed. Under sail. In 27 knots of wind. Yup.
So love that video, the first time I saw it, I thought of watching a ballet; a virtuoso performance.
Montanan is offline   Reply With Quote
Old 18-08-2020, 19:05   #105
Registered User
 
sanibel sailor's Avatar

Join Date: Feb 2013
Location: Ocala FL
Boat: 1979 Bristol 35.5 CB
Posts: 1,802
Re: Worst Med Mooring Ever - Just when you think you've seen everything!!

Quote:
Originally Posted by HeinSdL View Post
The difficulty is that you don't get hold of the bow mooring line until you have reached the quay with the stern. There is no anchoring involved. So to control the bow in this situation you would need to reverse smartly past one of the two boats already there and use them as 'support'. If all goes completely wrong and you end up side ways in that space then just let it be, use fenders as efficiently as possible and then pull the bow back out once you've got hold of the bow mooring line. In any case you can safely disregard the engine because it can help no more.

I figured that since he snagged the other boat's anchor chain that this was an anchoring arrangement
__________________
John Churchill Ocala, FL
NURDLE, 1979 Bristol 35.5 CB
Homeport currently Hudson Beach FL
sanibel sailor is offline   Reply With Quote
Reply

Tags
mooring

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Post the Worst "For Sale" Picture You've Seen. Jort Off Topic Forum 1126 12-04-2021 19:26
Just when you think you've seen it all reipot Off Topic Forum 2 17-10-2017 15:42

Advertise Here


All times are GMT -7. The time now is 05:47.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.